Conventionally, in a radio communication system by a cellular scheme, when a radio communication terminal apparatus starts or restarts communication, an individual channel between the radio communication terminal apparatus and the base station apparatus is not established yet, and the radio communication terminal apparatus is therefore designed to attempt an access to the base station apparatus using a random access channel (hereinafter “RACH”: Random Access Channel). For example, in the radio communication system by a W-CDMA scheme, a slotted ALOHA scheme is adopted. When each of a plurality of radio communication terminal apparatuses start or restart communication, access to the base station apparatus is attempted at an arbitrary timing out of start timing candidates (RACH subchannel). If there is no response from the base station apparatus within predetermined time from the access time, the access is determined failed, and access to the base station apparatus is attempted again (see, for example, Non-Patent Document 1).
Further, in the radio communication system by a multi-carrier transmission scheme, a technology is known in which when transmission packet is transmitted to the base station apparatus by RACH for establishing an individual channel, the radio communication terminal apparatus selects slot (timing) and subcarrier (frequency) of RACH and spreading code based on certain conditions, spreads the transmission packet by the selected spreading code, and then transmits the packet to the base station apparatus at the selected tuning and frequency (see, for example, Patent Document 1). Furthermore, in a technology disclosed in Patent Document 1, a radio communication terminal apparatus attempts an access to the base station apparatus, and if there is no response from the base station apparatus within predetermined time from the access time, the radio communication terminal apparatus attempts an access to the base station apparatus again.
Patent Document 1: Japanese Patent Application Laid-Open No. 2001-268051
Non-Patent Document 1: Keiji Tachikawa (ed.), “W-CDMA Mobile Communication Scheme,” Maruzen Co., Ltd., p. 45, Jun. 25, 2001